There has conventionally been proposed an image display apparatus using an organic EL (Electroluminescence) device that has a function of emitting light because of a recombination of a hole and an electron injected into a luminescent layer.
In the image display apparatus, a thin film transistor (TFT) made of, for example, an amorphous silicon or a polycrystalline silicon, or an organic light-emitting diode (OLED) that is one of an organic EL devices, constitute each pixel, and the respective pixels are arranged in a matrix. A suitable current value is set to the respective pixels and thus the brightness of each pixel is controlled, whereby a desired image is displayed.
There is an image display apparatus of an active matrix type including a plurality of pixels, each of which has a light-emitting device and a drive transistor such as a TFT arranged in series (for example, R. M. A. Dawson, et al. (1998). Design of an Improved Pixel for a Polysilicon Active-Matrix Organic LED Display. SID98 Digest, pp. 11 to 14).
A system for performing a light-emitting control for each pixel in the image display apparatus described above includes a batch emission system and a sequential emission system. In the batch emission system, a writing of a potential of an image signal to each pixel circuit is sequentially executed per a predetermined unit (for example, per a line, per a row, etc.), while a light-emitting control for the respective pixel circuits is executed all together for all pixel circuits. On the other hand, in the sequential emission system, the writing of the potential of the image signal to each pixel circuit and the light-emitting control to each pixel circuit are both sequentially performed per a predetermined group (for example, per a line, per a row, etc.).
Since a control of the writing of the potential of the image signal to each pixel circuit and the light-emitting control to each pixel circuit are both sequentially performed per a predetermined group in the sequential emission system, a peak of a load is distributed, so that an impact applied to a power source capacity of a power source apparatus is small. On the other hand, the light-emitting control is performed all together for all pixel circuits in the batch emission system, whereby the peak of the load is concentrated, and hence, the affect given to the power source capacity of the power source apparatus is increased. Therefore, when the scales (pixel numbers) of the pixel circuits are equal to one another, there arises a problem that a power source apparatus having a capacity greater than that of a power source apparatus used in the sequential emission system has to be prepared in the image display apparatus of the batch emission system.